Speed responsive apparatus



Dec. 28, 1937. CRQQKS 2,103,707

SPEED RESPONSIVE APPARATUS Filed Dec. '10, 1935 Reverse Link of Locomotive Valve Gear:

To Reset 11 11 Circuit.

INVENTOR Ravh K. Crooks dz ulwa HLS' ATTORNEY core I Patented Dec. 28, 1937 UNITED STATES PATENT OFFICE SPEED RESPONSIVE APPARATUS Application December 10, 1935, Serial No. 53,746

10 Claims.

My invention relates to speed responsive apparatus.

In connection with automatic speed control systems for railway trains a reset circuit is frequently provided, which circuit must be closed before the engineer can release the train brakes after an automatic brake application has been received. It is desirable to prevent the engineer from closing this circuit until the train has been brought to substantially a complete stop, and one object of my invention is the provision of novel and improved apparatus for accomplishing this desirable result.

The present application is closely related to a copending application, Serial No. 22,029, filed by H. L. Bone, on May 17, 1935, for Speed responsive apparatus, and the said Bone application contains claims which read on the present case.

I will describe one form of apparatus embodying my invention, and will then point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention.

Referring to the drawing, the reference character R. designates a relay which, in the form here shown, is of the usual and well-known type and comprises an inverted U -shaped magnetizable core l provided with two separate windings 2 and 3, one of which is disposed on each leg of the The relay R also comprises an armature H which cooperates with a fixed contact member H or a fixed contact member li to close a front contact i i---! l or a back contact ll-l i according as the armature H is picked up or released.

Associated with relay R are a suitable source of direct current, here shown as a battery B, a reactor L, and a switching device S.

The switching device S in the form here shown is of the toggle type and comprises a toggle arm 4 pivotally mounted intermediate its ends on a fixed pivot pin 5 for oscillation between two extreme positions. The toggle arm 4 is pivotally connected at its upper end with the lower end of a toggle rod 6, which toggle rod, in turn, is slidably mounted at its upper end in a fixed member '5, and surrounding the toggle rod 6 between an integral shoulder 6 and the fixed member i is a compressed coil spring 8 which biases the toggle arm to the nearest one of its two extreme positions. A resilient contact finger 9 is secured to, but insulated from, the lower end of the toggle arm 4', and this contact finger cooperates with two fixed contacts 9+9 and 9-9 in such manner that when the toggle arm occupies any position between its counterclockwise extreme position and a position just past its mid stroke position in a counter-clock- 5 wise direction, the finger 9 will engage the contact member 9 to close a contact 99 but that, when the toggle arm occupies any position between its clockwise extreme position and a position just past its mid stroke position in a clock- 10 wise direction, the contact finger 9 will then engage the contact member 9 to close a contact 99 The contact arm 4 is operatively connected by means of a pin and slot connection with an operating rod [0, which operating rod, in turn, is adapted to be operatively connected with any body or device whose linear or angular speed it is desired to measure, in such manner that the contacts 98- and 9-9 will be alternately opened and closed at a rate which varies with the speed of such body or device. In the particular embodiment here illustrated, the operating rod i9 is operatively connected with the reverse link l2 of the valve gear of a locomotive, which reverse link, as is well-known, is constantly oscillated when the locomotive is in motion, at a speed which varies with the speed of the locomotive. It will be apparent, therefore, that with the switching device arranged in the manner shown, the contacts 99 and 99 will be alternately operated when the locomotive is in motion at a rate which varies with the speed of the locomotive, but that, when the locomotive becomes stopped, one or the other of these contacts will always be closed regardless of the position which the driving mechanism of the locomotive then occupies. It will also be apparent that the time interval which elapses between the opening of either contact and the closing of the other contact will be very short.

The two windings 2 and 3 of relay R are separately connected with the battery B in series with the reactor L over the contacts 9-9 and 9-9 respectively, of the switching device S, in such manner that the current which flows in the reactor L when either winding 2 or 3 is energized will always flow through this reactor in the same direction, but that, the flux which is set up in the core i when the winding 2 is energized will thread this core in the opposite direction from that which is set up in this core when the winding 3 is energized.

The operation, as a whole, of the portion of I the apparatus thus far described is as follows:

When the locomotive of which the reverse link l2 forms a part is at rest, one or the other of the windings 2 or 3 of relay R will be constantly energized, according as contact 99 or contact 9-9 is then closed, and the parts are so proportioned that under these conditions the resultant flux which is set up in core I will cause armature H to pick up and close its front con tact H-I l When, however, the locomotive is in motion, the alternate operation of the contacts 99 and 9-9 will cause the windings 2 and 3 to become alternately energized and as a result, an alternating flux will then be set up in the core l, which flux will cause a pulsating torque to be exerted on the armature H. The magnitude of each torque impulse will depend upon the magnitude to which the current builds up in the winding which caused the impulse, and this latter magnitude, in turn, will depend upon the time constants of the circuits including the windings 2 and 3, and upon the rate at which the contacts El-B and 99 are operated. The parts are so proportioned that the windings 2 and 3 have a relatively low inductance compared to the inductance of the reactor L, but that the time constants of the circuits for the windings 2 and 3 are relatively large. It will be apparent, therefore, that as the speed of the locomotive increases, the magnitude of the torque impulses will decrease and the frequency of the torque impulses will increase. It will also be apparent that due to the fact that the current always flows in the same direction in the reactor L, and that the time which elapses between the opening of either contact l-3 or 9-9 and the closing of the other contact is very short, and that the inductances of the windings 2 and 3 are low compared to that of the reactor L, a very rapid reversal of the flux which is set up in core i will take place. The parts are further so proportioned that this reversal will be so rapid that the armature, due to its inertia, will be unable to follow the individual torque impulses even at very slow speeds of the locomotive. It follows, therefore, from the foregoing that as long as the speed of the locomotive is below a predetermined speed which depends upon the proportioning of the parts, the torque impulses which are exerted on the armature will have sumcient magnitude to cause the armature to pick up and remain picked up, but that, when the speed of the locomotive increases above said predetermined speed, the torque impulses which are then exerted on said armature will no longer have sufiicient magnitude to hold the armature picked up and the armature will therefore become released and remain in its released position, It is desirable that the speed of the locomotive above which the armature will be released and below which it will be picked up should be as low as possible, and the apparatus may be so constructed that this speed will be as low as three miles per hour.

The relay R may be used to control any suitable electroresponsive means, but when the apparatus is used in connection With automatic speed control systems of the type which causes the brakes of the locomotive to become automatically applied in the event that the locomotive speed exceeds a predetermined safe speed, the contact ll-I I of the relay will usually be connected in series, with the usual reset circuit in the manner shown, thus making it necessary for the engineer to wait until his train has been brought to substantially a complete stop after an automatic brake application has been received before he can release the brakes.

One advantage of apparatus embodying my invention is that due to the very rapid reversal of the flux in the core l which takes place when one winding of the relay becomes energized and the other winding becomes deenergized, the armature i will not bob up and down at any speed of the locomotive. This is very desirable when the speed responsive apparatus is used in connection with automatic speed control systems for trains of the type described hereinbefore.

Another advantage of apparatus embodying my invention is that all parts are of well-known construction, thus insuring the reliability of the apparatus and enabling the apparatus to be constructed at a minimum cost.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be madetherein Within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. Speed responsive apparatus comprising a pair of contacts which are alternately opened and closed at a variable rate, a relay having a magnetizable core provided with two separate windings, a reactor, a source of direct current, means for connecting each of said windings with said source in series with said reactor over a different one of said contacts in such manner that the resultant current which is supplied to said windings will always flow in the same direction in said reactor but will cause an alternating flux to be induced in said core, and an armature controlled by the alternating flux which is induced in said core, the parts being so proportioned that said armature will be constantly picked up or constantly released according as the rate at which said contacts are alternately opened and closed is below or above a relatively slow rate.

2. Speed responsive apparatus comprising a pair of contacts which are alternately opened and closed at a variable rate, a relay having a magnetizable core provided with two separate windings, a reactor, a source of direct current, means for connecting each of said windings with said source in series with said reactor over a difierent one of said contacts in such manner that the resultant current which is supplied to said windings will always flow in the same direction in said reactor but will cause an alternating flux to be induced in said core, and an armature controlled by the alternating flux which is induced in said core, the parts being so proportioned that said armature will become picked up when and only when the rate at which said contacts are alternately opened and closed is below a predetermined rate.

3. Speed responsive apparatus comprising a pair of contacts which are alternately opened and closed at a variable rate, a relay having a magnetizable core provided with two saparate windings, a reactor, a source of direct current, means for connecting each of said windings with said source in series with said reactor over a different one of said contacts in such manner that the resultant current which is supplied to said windings-will always flow in the same direction in said reactor but will cause an alternating flux to be induced in said core, and an armature controlled by the alternating flux which is induced in said core, the parts being so proportioned that said armature due to its inertia will be unable to follow the individual torque impulses caused by the alternating flux in said core, whereby said armature will remain constantly picked up or constantly released according as the rate at which said contacts are alternately opened and closed is below or above a predetermined rate.

4. Speed responsive apparatus comprising a pair of contacts which are alternately opened and closed at a variable rate, a relay having a magnetizable core provided with two separate windings, a reactor, a source of direct current, means for connecting each of said windings with said source in series with said reactor over a different one of said contactsin such manner that the resultant current which is supplied to said windings will always flow in the same direction in said reactor but will cause an alternating flux to be induced in said core, and an armature controlled by the alternating flux which is induced in said core, the parts being so proportioned that said armature due to its inertia will be unable to follow the individual torque impulses caused by the alternating flux in said core, whereby said armature will remain constantly picked up or constantly released according as the rate at which said contacts are alternately opened and closed is below or above a predetermined rate which depends upon the relative inductance of said windings and said reactor.

5. Speed responsive apparatus comprising a pair of contacts which are alternately opened and closed at a variable rate, a relay having a magnetizable core provided with two separate windings, a reactor, a source of direct current, means for connecting each of said windings with said source in series with said reactor over a different one of said contacts in such manner that the resultant current which is supplied to said windings will always flow in the same direction in said reactor but will cause an alternating flux to be induced in said core, and a contact controlled by said relay in such manner that said contact will be constantly closed or constantly opened according as the rate at which said first mentioned contacts are alternately opened and closed is below or above a predetermined rate which depends upon the proportioning of the parts.

6. Speed responsive apparatus comprising a pair of contacts which are alternately opened and closed at a variable rate in such manner that the time interval which elapses between the opening of either contact and the closing of the other contact is relatively short, a relay having a core and two relatively low inductance windings on said core, a reactor having a relatively high inductance compared to the inductance of said relay windings, a source of direct current; a circuit for one of said windings including said source, said reactor and one of said contacts; a circuit for the other winding including said source, said reactor, and the other contact; said two windings and said reactor being connected in said two circuits in such manner that the current which is supplied to said windings over said circuits will always flow in the same direction in said reactor but will set up an alternating flux in said core, and an armature controlled by said relay and having its inertia so chosen with respect to the time constants of said circuits that said armature will be constantly picked up or constantly released according as the rate at which said contacts are alternately opened and closed is below or above a predetermined rate.

'7. Speed responsive apparatus comprising a relay provided with a core and with two separate windings on said core, a reactor, means for alternately supplying said windings connected in series with said reactor with direct current at a variable rate in such manner that an alternating flux will be set up in said core but that the current will always flow in the same direction in said reactor, and a contact controlled by said relay in such manner that said contact will be constantly closed or constantly opened according as the rate at which current is alternately supplied to said windings is below or above a predetermined rate which depends upon the proportioning of the parts.

,8. Speed responsive apparatus comprising a relay provided with a core and with two separate windings on said core, a reactor, means for alternately supplying said windings connected in series with said reactor with direct current at a variable rate in such manner that an alternating flux will be set up in the core of said relay but that the current will always flow in the same direction in said reactor, and an armature controlled by the alternating flux set up in said core, the parts being so proportioned that said armature will be constantly picked up or constantly released according as the rate at which said windings are alternately supplied with current is below or above a predetermined rate.

9. Speed responsive apparatus comprising a relay provided with a core and with two separate windings on said core, a reactor, means for alternately supplying said windings connected in series with said reactor with direct current at a variable rate in such manner that an alternating flux will be set up in the core of said relay but that the current will always flow in the same direction in said reactor, and an armature controlled by the alternating fiux set up in said core, the parts being so proportioned that said armature will become picked up when and only when the rate at which said windings are alternately supplied with current is below a predetermined rate.

10. Speed responsive apparatus comprising a relay provided with a core and with two separate windings on said core, a reactor, means for alternately supplying said windings connected in series with said reactor with direct current at a variable rate in such manner that an alternating flux will be set up in the core of said relay but that the current will always flow in the same direction in said reactor, and an armature controlled by said relay, said armature being constructed to have sufficient inertia to cause it to constantly occupy its released or its attracted position according as the rate at which said windings are alternately supplied with current is above or below a predetermined rate.

RALPH K. CROOKS. 

